1.  Legalistic teachers we troubling the Philippians (as they do Christians today), particularly concerning the issue of circumcision.  The Jews focused on circumcision as a sign of the covenant relationship between them and God but missed that circumcision was not meant to be external only but circumcision of the heart (the cutting away of sin).  Deut 30:6; Rom 2:28,29

2.   The true circumcision are those who: worship God in the spirit (that is not religion of ritual, law or external observance but of the heart, true devotion of heart, mind and live to God (Gal 6:15); who glory (boast) only in Jesus Christ not in their accomplishment; and place no confidence in the flesh (either circumcision of the flesh or the flesh referring to all that we are apart from Christ, inner selfishness, the sin nature.

3.  Paul’s burning desire even after decades of salvation was to know Christ more and more.  He never lost the wonder of grace.